Monsoon-driven biogeochemical dynamics in an equatorial shelf sea: Time-series observations in the Singapore Strait

Martin, Patrick; Moynihan, Molly A.; Chen, Shuang; Woo, Oon Yee; Zhou, Yongli; Nichols, Robert S.; Chang, Kristy; Tan, Ashleen S. Y.; Chen, Ying‐Hsuan; Ren, Haojia; Chen, Mengli

doi:10.1016/j.ecss.2022.107855

Cited by 18 publications

(18 citation statements)

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“…The Singapore Strait is subject to two monsoon seasons, and the prevailing ocean current reverses direction between the two (Figure 1; van Maren and Gerritsen, 2012). The northeast (NE) monsoon from mid-November to early March brings relatively saline water from the South China Sea, while the southwest (SW) monsoon from mid-May to mid-September brings lower-salinity water carrying terrestrial inputs (Zhou et al, 2021) and higher nutrient concentrations (Martin et al, 2022). During the inter-monsoon seasons, residual flows are weak, salinity increases, and nutrient concentrations are very low.…”

Section: Site Description and Study Designmentioning

confidence: 99%

“…The sampling and analytical methods for dissolved and particulate carbon and nutrients, and for chlorophyll-a are described fully in Zhou et al (2021) and Martin et al (2022). Briefly, dissolved carbon and nutrient samples were filtered on board through 0.2 µm Supor membranes, then frozen at -20°C (nutrients) or acidified and stored at +4°C (DOC).…”

Section: Seawater Sampling and Analysismentioning

confidence: 99%

“…Three incubation experiments were conducted to test whether changes in DIP or labile DOC influence water-column APA (in January, March and June 2019). Incubations were only conducted at Kusu reef; however, as the water column biogeochemical parameters show much greater seasonal than spatial variability across the Singapore Strait (Martin et al, 2022) the results of these incubations should be considered reflective of the Singapore Strait generally.…”

Section: Seawater Incubations To Assess Drivers Of Water-column Apamentioning

confidence: 99%

“…Except for APA and ATP, the water column biogeochemistry data used here were analysed in detail by Martin et al (2022) and Zhou et al (2021), who showed that there is distinct seasonal variability chiefly in the dissolved parameters as a result of the seasonal advection of freshwater and terrestrial inputs to the Singapore Strait. The most important biogeochemical data for the present analysis are plotted as time series in Fig.…”

Section: Water Column Biogeochemistry and Apa Ratesmentioning

confidence: 99%

“…3; parameters that are not shown in Fig. 3 are plotted in Martin et al (2022). Briefly, salinity was highest during the late NE monsoon and intermonsoon seasons, ranging between 32-33, but was reduced to 29-31 throughout the SW monsoon, and also decreased to about 30-31 during the early NE monsoon.…”

Section: Water Column Biogeochemistry and Apa Ratesmentioning

confidence: 99%

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High rates of alkaline phosphatase activity in an equatorial coral reef ecosystem unrelated to seasonal nutrient dynamics

Nichols

Moynihan

Martin

2022

Preprint

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Coral reef productivity depends on fast nutrient cycling, mediated largely by enzymatic breakdown of organic matter. Alkaline phosphatases hydrolyse phosphomonoesters and are one of the key enzymes involved in marine phosphorus cycling. They are expressed by a plethora of marine organisms including both planktonic microbes and metazoans such as corals, often in response to phosphate limitation, and are potentially important for coral P nutrition and reef biogeochemical cycling. However, most alkaline phosphatase activity (APA) data are from open-ocean environments, and the rates and drivers of APA in coastal waters are not well understood. Here, we measured APA both in the water column and associated with three coral species at reefs in Singapore, where the monsoonal ocean current reversal creates strong seasonal changes in dissolved nutrient availability. Water column APA was consistently high, averaging 9 ± 10 nmol l-1 h-1, but was not correlated with dissolved phosphate or other biogeochemical parameters. Experimental phosphate addition did not reduce seawater APA but addition of labile organic carbon did increase seawater APA, indicating that the increase in APA was driven by heterotrophic activity rather than phosphate stress. Coral APA ranged from 12–163 µmol m-2 h-1 depending on species and was equivalent to the APA in several meters of overlying water. While most coral APA was associated with the coral holobiont rather than the coral mucus, corals released 12 – 55 µmol h-1 per m2 of mucus-associated APA into the water column, which is potentially significant for water column DOP cycling.

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Section: Site Description and Study Designmentioning

confidence: 99%

Section: Seawater Sampling and Analysismentioning

confidence: 99%

Section: Seawater Incubations To Assess Drivers Of Water-column Apamentioning

confidence: 99%

Section: Water Column Biogeochemistry and Apa Ratesmentioning

confidence: 99%

Section: Water Column Biogeochemistry and Apa Ratesmentioning

confidence: 99%

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